Create test-specific temp directories to get the tests passing.

test/unit-tests.js

@@ -1,3 +1,5 @@
+const fs = require('fs');
+const path = require('path');
 const grunt = require('grunt');
 const jsonlint = require('@prantlf/jsonlint');
 const validator = require('@prantlf/jsonlint/lib/validator');
@@ -264,12 +266,16 @@ function testReformattingFile(indent) {
     }
   }
 
+  // Grunt <= 1.5 always tries to create the directory on Linux, even when it exists.
+  // Let's give it a new directory.
+  const temp = path.dirname(fs.mkdtempSync(`${__dirname}${path.sep}`));
+
   // Build an unformatted file for testing.
-  grunt.file.write(`${__dirname}/reformat-this.json`, '{"somethingsomething":"something","something":"dark side"}');
+  grunt.file.write(`${__dirname}/${temp}/reformat-this.json`, '{"somethingsomething":"something","something":"dark side"}');
 
-  runWithFiles(grunt, jsonlint, [ 'test/reformat-this.json' ], options);
+  runWithFiles(grunt, jsonlint, [ `test/${temp}/reformat-this.json` ], options);
 
-  const formatted = grunt.file.read(`${__dirname}/reformat-this.json`);
+  const formatted = grunt.file.read(`${__dirname}/${temp}/reformat-this.json`);
   const lines = formatted.split(/\r?\n/);
   expect(lines).to.have.length(5);
   expect(lines[0]).to.be('{');
@@ -278,7 +284,7 @@ function testReformattingFile(indent) {
   expect(lines[3]).to.be('}');
   expect(lines[4]).to.be.empty();
 
-  grunt.file.delete(`${__dirname}/reformat-this.json`);
+  grunt.file.delete(`${__dirname}/${temp}/reformat-this.json`);
 }
 
 function testSortingObjectKeys() {